1. Field of the Invention
The present invention relates to an image-forming device for recording images on a recording medium by ejecting ink droplets thereonto, in which ink cartridges are detachably mounted on an ink cartridge mounting unit. More particularly, the invention relates to an ink cartridge positioning and locking mechanism for accurately positioning and fixing the ink cartridges on the ink cartridge mounting unit.
2. Description of the Related Art
Ink jet printers have been used extensively as they are simple in structure and are capable of high quality high speed printing. Typically, the ink jet printers include an ink jet head, an ink jet mounting unit, and an ink cartridge. The ink jet head ejects ink droplets onto a recoding medium to thereby form images thereon. The mounting unit supports the ink jet head and is mounted on the carriage that moves in the widthwise direction of the print paper. The ink cartridge stores ink therein and is detachably mounted on the mounting unit.
The ink cartridge is formed with an ink supply port at its bottom for supplying ink to the ink jet head. In order to mount the ink cartridge on the mounting unit, the ink supply port is firstly engaged with the corresponding part in the mounting unit, and then a locking arm swingably provided at an upper portion of the head holder is moved downward toward the ink cartridge to press the ink cartridge downward. As a result, the ink cartridge is fixedly mounted on the mounting unit.
However, the ink cartridge mounted on the mounting unit tends to move as the carriage moves back and forth at a high speed. More specifically, the ink cartridge swings or vibrates about the ink supply port in the direction in which the carriage moves, with a result that ink in the ink cartridge is shifted to one side and thus using all the ink is impossible. Provision of another locking member may prevent the ink cartridge from swinging, however, this makes the entire structure complicated and mounting and detaching operation of the ink cartridge becomes complicated.
In view of the foregoing, it is an object of the invention to provide an ink cartridge positioning and looking mechanism that enables an ink cartridge or a set of ink cartridges to accurately position and fix on an ink cartridge mounting unit.
It is another object of the invention to provide an image-forming device that has a corresponding structure allowing the ink cartridge to be mounted.
To achieve the above and other objects, an ink cartridge of the invention includes a bottom wall that is substantially a rectangular shape, a first side wall (front side wall), a second side wall (rear side wall), a third side wall (right side wall), a fourth side wall (left side wall), and a top wall, thereby forming a substantial box shape and defining an inner space. A first engaging depression is formed in the bottom wall in a position nearer to the left side wall. When the ink cartridge is mounted on the cartridge mounting unit, the first engaging depression engages an engaging protrusion formed in the mounting unit. An ink supply port is formed in the bottom wall. The ink supply port is provided in a position nearer to the right side wall. The ink supply port is brought into engagement with an ink supply channel fluidly connected to the head unit.
A second engaging depression is formed in the top wall in a position corresponding to a center position between the first engagement depression and the ink supply port. The engaging pawl of a looking arm engages the second engaging depression when the locking arm locks the ink cartridge to the head unit. Further, a pair of ribs is provided on the left side wall to oppose each other with a prescribed interval. An engaging protrusion protrudes from the head unit and fits into the spaced between the interval of the ribs when the ink cartridge is mounted in the head unit.